<s>
The	O
automatic	B-Application
calculation	I-Application
of	I-Application
particle	I-Application
interaction	I-Application
or	I-Application
decay	I-Application
is	O
part	O
of	O
the	O
computational	B-Algorithm
particle	I-Algorithm
physics	I-Algorithm
branch	O
.	O
</s>
<s>
The	O
goal	O
of	O
the	O
automation	O
is	O
to	O
handle	O
the	O
full	O
sequence	O
of	O
calculations	O
in	O
an	O
automatic	O
(	O
programmed	O
)	O
way	O
:	O
from	O
the	O
Lagrangian	O
expression	O
describing	O
the	O
physics	O
model	O
up	O
to	O
the	O
cross-sections	O
values	O
and	O
to	O
the	O
event	B-Algorithm
generator	I-Algorithm
software	O
.	O
</s>
<s>
Particle	O
accelerators	O
or	O
colliders	O
produce	O
collisions	O
(	O
interactions	O
)	O
of	O
particles	O
(	O
like	O
the	O
electron	O
or	O
the	O
proton	B-Application
)	O
.	O
</s>
<s>
The	O
colliding	O
particles	O
form	B-Language
the	O
Initial	O
State	O
.	O
</s>
<s>
But	O
particle	O
physics	O
is	O
now	O
requiring	O
much	O
more	O
complex	O
calculations	O
like	O
at	O
LHC	O
where	O
are	O
protons	B-Application
and	O
is	O
the	O
number	O
of	O
jets	O
of	O
particles	O
initiated	O
by	O
proton	B-Application
constituents	O
(	O
quarks	B-Operating_System
and	O
gluons	O
)	O
.	O
</s>
<s>
They	O
help	O
constructing	O
event	B-Algorithm
generators	I-Algorithm
and	O
are	O
sometimes	O
viewed	O
as	O
generators	O
of	O
event	B-Algorithm
generators	I-Algorithm
or	O
Meta-generators	O
.	O
</s>
<s>
To	O
simulate	O
the	O
production	O
of	O
events	O
through	O
event	B-Algorithm
generators	I-Algorithm
,	O
3	O
steps	O
have	O
to	O
be	O
taken	O
.	O
</s>
<s>
II	O
Matrix	O
element	O
code	O
generation	O
:	O
Various	O
methods	O
are	O
used	O
to	O
automatically	O
produce	O
the	O
matrix	O
element	O
expression	O
in	O
a	O
computer	O
language	O
(	O
Fortran	B-Application
,	O
C/C	B-Language
++	I-Language
)	O
.	O
</s>
<s>
for	O
the	O
couplings	O
)	O
produced	O
by	O
step	O
I	O
or	O
model	O
specific	O
libraries	O
constructed	O
by	O
hands	O
(	O
usually	O
heavily	O
relying	O
on	O
Computer	B-Algorithm
algebra	I-Algorithm
languages	O
)	O
.	O
</s>
<s>
III	O
Event	B-Algorithm
generator	I-Algorithm
code	O
generation	O
:	O
This	O
code	O
must	O
them	O
be	O
interfaced	O
to	O
other	O
packages	O
to	O
fully	O
provide	O
the	O
actual	O
final	O
state	O
.	O
</s>
<s>
Parton	O
showering	O
describing	O
the	O
way	O
final	O
state	O
quarks	B-Operating_System
or	O
gluons	O
due	O
to	O
the	O
QCD	O
confinement	O
generate	O
additional	O
quark/gluon	O
pairs	O
generating	O
a	O
so-called	O
shower	O
of	O
partons	O
before	O
transforming	O
into	O
hadrons	O
.	O
</s>
<s>
Hadronization	O
describing	O
how	O
the	O
final	O
quark	B-Operating_System
pairs/triplets	O
form	B-Language
the	O
visible	O
and	O
detectable	O
hadrons	O
.	O
</s>
<s>
Underlying	O
event	O
takes	O
care	O
of	O
the	O
way	O
the	O
rest	O
,	O
in	O
term	O
of	O
constituent	O
,	O
of	O
the	O
initial	O
protons	B-Application
also	O
contribute	O
to	O
any	O
given	O
event	O
.	O
</s>
<s>
It	O
dates	O
back	O
to	O
the	O
1960s	O
when	O
packages	O
such	O
as	O
SCHOONSCHIP	B-Application
and	O
then	O
REDUCE	B-Language
had	O
been	O
developed	O
.	O
</s>
<s>
Such	O
codes	O
have	O
evolved	O
quite	O
a	O
lot	O
with	O
applications	O
not	O
only	O
optimized	O
for	O
high-energy	O
physics	O
like	O
FORM	B-Language
but	O
also	O
more	O
general	O
purpose	O
programs	O
like	O
Mathematica	B-Language
and	O
Maple	B-Language
.	O
</s>
<s>
The	O
first	O
automatic	O
system	O
incorporating	O
all	O
the	O
steps	O
for	O
the	O
calculation	O
of	O
a	O
cross	O
section	O
,	O
from	O
Feynman	O
graph	O
generation	O
,	O
amplitude	O
generation	O
through	O
a	O
REDUCE	B-Language
source	O
code	O
that	O
produces	O
a	O
FORTRAN	B-Application
code	O
,	O
phase	O
space	O
integration	O
and	O
event	O
generation	O
with	O
BASES/SPRING[17]	O
is	O
GRAND[18]	O
.	O
</s>
<s>
The	O
initial	O
and	O
final	O
state	O
particles	O
can	O
be	O
elementary	O
particles	O
like	O
electrons	O
,	O
muons	O
,	O
or	O
photons	O
but	O
also	O
partons	O
(	O
protons	B-Application
and	O
neutrons	B-Device
)	O
.	O
</s>
<s>
The	O
bare	O
partons	O
that	O
do	O
not	O
exist	O
in	O
nature	O
(	O
they	O
are	O
confined	O
inside	O
the	O
hadrons	O
)	O
must	O
be	O
so	O
to	O
say	O
dressed	O
so	O
that	O
they	O
form	B-Language
the	O
known	O
hadrons	O
or	O
mesons	O
.	O
</s>
<s>
When	O
the	O
initial	O
state	O
particles	O
are	O
protons	B-Application
at	O
high	O
energy	O
,	O
it	O
is	O
only	O
their	O
constituents	O
which	O
interact	O
.	O
</s>
<s>
Automatic	O
software	O
packages	O
can	O
be	O
useful	O
in	O
exploring	O
a	O
number	O
of	O
Beyond	O
the	O
Standard	B-General_Concept
Model	I-General_Concept
(	O
BSM	O
)	O
theories	O
,	O
such	O
as	O
the	O
Minimal	O
Supersymmetric	O
Standard	B-General_Concept
Model	I-General_Concept
(	O
MSSM	O
)	O
,	O
to	O
predict	O
and	O
understand	O
possible	O
particle	O
interactions	O
in	O
future	O
physics	O
experiments	O
.	O
</s>
<s>
Maple	B-Language
,	O
Mathematica	B-Language
often	O
need	O
to	O
consider	O
abstract	O
,	O
mathematical	O
structures	O
in	O
subatomic	O
particle	O
collisions	O
and	O
emissions	O
.	O
</s>
